If you look at the history of this temple - sreepadmanabhaswamytemple.org/history.htmIn 1686 A.D. the Temple was almost fully destroyed in a major fire accident. Work on the re- construction of the Temple was started only in 1724...... In 1730 the idol was again moved to ‘Balalaya’ prior to the renovation and reconstruction of the sanctum sanctorum. It took two years for completion. The old wooden idol was replaced by the one that we see today. So the idol that we see today is pretty recent. Who knows whether the original idol had any Shiva linga under the hand...
– Lazy LubberApr 15 at 4:56

@LazyLubber Most of the images on net showing Shiva Linga
– user17294Apr 15 at 5:26

Thats ok. That could be the current idol. My point is - who knows whether this was the case with the original idol?
– Lazy LubberApr 15 at 5:28

2

@LazyLubber The people who saw the original idol were alive. I dont think the new idol was made without any guidance
– user17294Apr 15 at 5:29